The increasing number of infants and young children receiving cochlear implants today has created significant challenges for clinicians charged with device fitting. A long term objective of the PI is to exploit objective electrophysiological measures to help clinicians more accurately fit cochlear implants. One measure that has proven to have strong correlation with the preferred upper limit of stimulation is the electrical stapedius reflex threshold (ESRT), typically measured indirectly by recording acoustic impedance changes of the contra-lateral eardrum. Unfortunately 30-40% of patients do not register detectable acoustic impedance changes even at high stimulation levels. Furthermore, these measurements are often cumbersome to obtain in young children. The current proposal seeks to develop and evaluate the feasibility of using electromyograms recorded from the stapedius (stEMGs) as an alternative. Utilizing animal models implanted with cochlear electrodes supplemented by anatomical evaluations in human temporal bones, the research has two specific aims: 1) Characterize the stEMG response properties as a function of stimulation parameters in animal models, comparing stEMG response growth with other objective measurements and 2) Determine design constraints and feasible placement strategies for the stEMG electrode to enable the development of an electrode prototype for eventual human application. Since recording the stEMG does not necessarily require an intact middle ear and eardrum it is likely to be recordable in a larger number of patients. This signal could eventually be integrated with commercially available implant telemetry systems offering additional information on implant integrity and the underlying auditory system, or in the future serve as feedback to the speech processor to modulate sound sensitivity. [unreadable] [unreadable] [unreadable]